More than two million people have looked at the BBC News website's missing persons boards after the Tsunami disaster. But what role do they play in news coverage and how is the information checked?

A Buddhist monk looks at the missing and dead numbers displayed in Phuket

It was obvious from the first emails coming into the BBC on Boxing Day that this was going to be a tragedy like no other the website had covered.

Within hours of the waves striking, first hand accounts from the affected areas came in from Madras, the Maldives, Phuket, and Sri Lanka. Among them were pleas from loved ones - can you find my daughter, my father, my friends?

At times of disaster people turn to the BBC, not just for its reporting, but as we now know, for specific information about them and their families.

When they cannot get through on the conventional routes such as the Foreign Office helpline or via charitable organisations, they expect the BBC with its global network to have some answers.

It is not something we've ever done before on such a large scale.

Gujarat earthquake

During the Gujarat earthquake four years ago, we noticed people were using our debate pages to trace their relatives.

As the extent of the tsunami became clear - we realised this was going to be on a vast scale.

Well over two million people have looked at the pages. These desperate messages were read out on other BBC outlets; World, News 24, and Radio Five Live.

And word spread round the internet community that this service was being offered by the BBC.

For a small team, which was not expected to be in the office over the Christmas period, staff came back early from their holidays and freelancers volunteered to help.

What everyone noticed was these missing persons boards were making a difference.

Although too many of the messages we posted will not find a happy ending, through the web we were able to reunite several families.

At times like this - any information, however small or tenuous, is grabbed as a lifeline.

Dutchman Rob Delissen traced his brother, sister-in-law and their two-year-old child by tracking down someone who had posted a message from a remote Thai island.

He went on to tell his story to the BBC and to other international broadcasters too.

Ruth Ling, from London, posted her message to trace a friend, and a stranger from Lancashire called her by phone to say he'd heard her friend was safe in Colombo.

There were many more such examples.

Public service role

A foreigner walks past notices of missing people at city hall in Phuket

The popularity of the message boards and our public service role in hosting them has raised many questions for us.

How do we know people are telling us the truth? Of course, we cannot know absolutely the information people are giving us is 100% accurate.

What we did do is make sure we didn't publish any information about someone's death until we had verified it and spoken to the families or those who sent messages.

We decided not to publish telephone numbers or personal email addresses. We emailed people back and chased up any specific leads in the usual journalistic way.

But even though some of the information was not absolutely verifiable at the time, the missing persons boards were something that was absolutely right for us to do in the circumstances.

We'll learn from it if we have ever to do such a thing again.

For me, the two things that stand out from the past two weeks, is the extent to which the BBC is relied upon as a notice board for the world, and the basic generosity of people to share their information in order to make a horrific ordeal more bearable for countless numbers of people.